Adjustable ladder



FIG. 1 is a front view of an adjustable ladder;

FIG. 2 is a rear view thereof;

FIG. 3 is a left view thereof;

FIG. 4 is a right view thereof;

FIG. 5 is a bottom side view thereof;

FIG. 6 is a top side view thereof;

FIG. 7 is a extend view thereof;

FIG. 8 is an enlarged view of FIG. 5; and,

FIG. 9 is an enlarged view of FIG. 6.

The broken lines are for the purposes of illustrating portions of the adjustable ladder and form no part of the claimed design. 

CLAIM The ornamental design for an adjustable ladder, as shown and described. 